Characterization of underwater acoustic propagation from a rocket launch
Abstract
Over 80% of global ocean basins’ bathymetry are currently indirectly estimated using satellite measurements of marine gravity anomalies infer bathymetry. Where available, ship-based soundings can help constrain satellite-based techniques, and result in potentially more accurate bathymetric products. Their use, however, requires the presence of a sound source aboard a vessel, which can present logistical challenges. Sound sources of opportunity such as commercial vessels can help alleviate these logistical challenges, but their use is limited to well-established shipping channels. This proposal explores the possibility of using airborne sources of sound, such as a rocket launch, to infer bathymetry. If found feasible, the technique can greatly alleviate the time taken to conduct bathymetric surveys. In order to effectively utilize an airborne source of sound to infer bathymetry at full ocean depth, an important first step is to establish whether the signal intensity upon penetration into the water column is of sufficient strength to reflect off the ocean bottom and retain sufficient energy to be measurable near the ocean surface. The significant intensity associated with a rocket launch presents a unique opportunity to analyze the bottom reflection to extract water column depth. Here, we propose a systematic measurement effort that will measure the acoustic signature of a Falcon 9 rocket launch conducted by SpaceX on Vandenberg Air Force Base in Central California. Three hydrophones will be coupled with in-air microphones using surface spar buoys deployed in water depths of 100 m, 500 m and 1 km along the ground projection of a rocket launch. Additionally, the 100 m station will consist of a bottom-mounted directional acoustic array, capable of resolving the various underwater propagation paths. The resulting measurements and analysis will provide an insight into underwater signal levels from a loud in-air source, and establish if the bottom-reflected path can be exploited for bathymetric inversion.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 15, 2019
- Source ID
- N000141912516
Entities
People
- Kaustubha Raghukumar
Organizations
- Integral Consulting (United States)
- Office of Naval Research
- United States Navy